1. Field of the Invention
The present invention relates generally to devices and methods for optically analyzing biological fluids. In particular, it relates to the design and use of centrifugal rotors which allow release of a predetermined volume of a fluid in response to mounting the rotor in a centrifuge.
Blood plasma and other biological tests frequently require that predetermined volumes of liquids be quickly and completely mixed with a biological fluid for analysis in a variety of optical tests or assays. It is also desirable to separate potentially-interfering cellular components of the material from the biological fluid prior to testing. Such mixing and separation steps have heretofore been typically performed by centrifugation to separate, for instance, blood plasma from the cellular components, followed by manual or automated pipetting of predetermined volumes of the blood plasma into separate test wells for optical analysis. Such procedures are labor-intensive and time-consuming, and various automated systems and methods have been proposed for providing multiple aliquots of plasma suitable for testing in a more efficient manner.
Prior art rotors have frequently utilized complex designs which are difficult and costly to manufacture. Often, the rotors require various separable parts or components which are brought together or separated at different points in the centrifugation procedure. Previous centrifugal rotors have often been limited in the number of discrete samples and test wells which they can provide, and in some cases require the use of a separate displacement fluid to effect flow of blood and plasma through the system.
For these reasons, it would be desirable to provide improved centrifugal rotors and methods suitable for quickly and easily delivering a predetermined volume of liquid to a receiving chamber in the rotor. The methods should be simple and be capable of being performed in relatively short times. In particular, the methods should require relatively few steps and should be capable of being performed with little or no intervention or manipulation by the operator.
2. Description of the Background Art
U.S. Pat. No. 4,999,304 discloses a centrifuge for separating constituents of fluids comprising a separate diluent chamber. U.S. Pat. No. 4,963,498 discloses devices which rely upon capillaries, chambers, and orifices to pump and mix fluids for optical analysis. U.S. Pat. No. 4,898,832 discloses an analytical rotor comprising a series of reagent chambers. U.S. Pat. No. 4,814,144 discloses a centrifugal rotor into which various reagents may be introduced. U.S. Pat. No. 4,756,883 relates to a centrifugal rotor comprising various reagents in a dry tabletized form. U.S. Pat. No. 4,743,558 is directed to a rotor having a plurality of storage chambers for liquid reagents. U.S. Pat. No. 4,412,973 discloses a rotor comprising a reagent container having an outwardly disposed tip. The tip is broken off and the container is opened by tilting the container. U.S. Pat. No. 4,387,164 discloses a rotor having a reagent contained within a carrier solid organic binder which is fixed within the rotor. European Patent Application No. 8,105,106.0 discloses a reagent container which is opened as the result of centrifugal force.